Flashlight lamp



y 1951 J. A. DE VRIEND El AL 2,554,094

msnucn'r LAMP Filed March 1, 1949 nvvE/vroR-s JonANrvzd ADE/MN DE VR/END GERARD DAN/E1. RIECK AGENT Patented May 22, 1951 FLASHLIGHT LAMP Johannes Adriaan de Vriend and Gerard Daniel Rieck, Eindhoven, Netherlands, assignors to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application March 1, 1949, Serial No. 78,996 In the Netherlands April 5, 1948 6 Claims.

The present invention relates generally to flash lamps, and more particularly to those flash lamps constructed to have a long 50% flash time. Such flash lamps are used to advantage in photographic apparatus comprising a slow-action focal-plane shutter; The term 50% flash-time is to be understood here to mean the time between the moment at which the light intensity has increased to 50% of its maximum value and the moment at which the light intensity has decreased to 50% of its maximum value.

In a flash-light lamp the closed bulb of which contains a filling of oxygen gas with which a substance such as aluminium, magnesium, or an alloy thereof produces an actinic reaction, steps have been made to increase the 50% flash-time by the use of a mixtur consisting of nitrous oxide (N20) and oxygen. In order to obtain a noticeable result, it is necessary to add to oxygen a fairly large amount, for example more than 30% by volume, of nitrous oxide and this involves the necessity of increasing the pressure of the gas-mixture filling in order to have-available an amount of oxygen sufficient for the actinic reaction.

The object of the invention is also to realise a long 50% flash-time with the use of an auxiliary gas, but without involving the disadvantage of a material increase in the pressure of th gaseous filling and the attendant risk. of breakage of the bulb caused by the actinic reaction.

The present invention relates to a flash-light lamp the closed bulb ofwhich contains oxygen and a material producing therewith an actinic reaction, and it has the characteristic that the gaseous filling contains an auxiliary gas retarding the combustion and comprising a halogencontaining compound of boron, carbon, silicon, titanium, germanium or tin with a combustion heat lower than 200 kgs. cal./mol.

As an alternative, the auxiliary gas may comprise a mixture of the said compounds.

In order to make the invention better understood, it is mentioned that the kind and the quantity of an auxiliary gas used according to the invention, together with the oxygen pressure, the kind of the material producing an actinic reaction and the dimensions all contribute to affect the extent of retardation of the combustion by the auxiliary gas and hence the increase of the 50% flash-time. The use of an amount of auxiliary gas smaller than 10% by volume of the gaseous filling may result in material increase of the 50% flash-time.

It is noted that an auxiliary gas is required to have a vapour tension such that it may be used, at the operating temperature, in sufiicient concentration to ensure noticeable retardation of the combustion or increase in the 50% flash-time. Thus, for example, perchloroethylene will not be used in practice because of its low vapour tension at operating temperature. As a result, this gas provides only a small increase in the 50% flashtime. Furthermore, it is mentioned that the serviceability of an auxiliary ga in practice is also determined by its reactivity at operating temperature with the substances contained in the bulb. Substances such as chlorine and hydrochloric-acid gas whilst having a retarding effect upon the actinic reaction attack the igniting filament so readily that merely for this reason they are unserviceable for the purpose considered. Carbon tetrachloride and trichloroethylene are particularly suitable for use of the invention in connection with the value of their vapour tension and the important increase in 50% flash-time that is obtainable. The flash-time increasing efiect of the first-mentioned substance is somewhat smaller than that of carbon tetrachloride.

The table following hereinafter shows the influence exerted by some auxiliary gases according to the invention upon a given flash-light lamp, the bulb of which contains material producing an actinic reaction and comprisin an aluminium-magnesium alloy and oxygen.

A flash-light lamp of the kind with which the results mentioned in the table are obtained is shown in the accompanying drawing as an ex ample of a flash-light lamp according to the invention.

Reference numeral lo indicates the circular glass bulb having a section of 55 mms. and a volume of about ccs. The bulb contains a filling ll of wire consisting of an alloy of aluminium with 7% by weight of magnesium having a weight of 54 mgs. and a diameter of the wire of 32 microns and furthermore contains a gas mixture according to the invention which is designated l2 and the composition and pressure of which are shown in Table 1. I

The flash-light lamp comprises two current supply wires l3, each of which is secured at one extremity in a cap [4 and which are connected at the other extremities to a double igniting wire it: having a length of 2 mms. and a diameter of 18 microns and which is provided with an igniting paste it constituted by phosphorus and lead peroxide.

Table Pressure 50% flash- Combustion Vol. per gaseous Retardm as t1me 10 heat g g cent g sec, k. caL/mol.

. 3O (calcu- BC] 6 45 35 ca 3 10 o 40 med) 5.3 47 34 6.6 50 35 8 50 35 2 46 27 CHO]: 1o.

8 50 31 3 45 33 OHC1=CCI2 6 45 37 021.140

10 50 40 4 45 26 CHzClz 10 5O 28 107.

, 20 55 35 2 45 26 CH3G1 6 45 34 164.

10 50 3O 2 45 23 CH3B1 6 45 27 184.

10 50 31 2 45 29 CHaJ 6 45 30 195.

3 2 33 5 10 (calcu- S1014 e 45 33 g lated). Sim 6 45 30 ca. 173 (calcu- 10 5o 37 med)- TiCh l 45 27 ca. 34 (calculated). 2 45 32 GeCh 6 45 39 ca. 5 (calcu- 2 22 $3 lt y 1 ca. ca cu- 3.3 45 27 lated). nil 0 45 20 What we claim is:

1. A flash-lamp comprising a closed transparent bulb, an actinically reactive material in said bulb, and a gaseous filling in said bulb; said gaseous filling comprising oxygen for reacting with said actinically reactive material, and an auxiliary combustion-retarding gas; said auxiliary gas comprising a halogen containing compound of one of the elements of the group boron, carbon, silicon, titanium, germanium and tin, and having a combustion heat lower than 200 kgs. cal./mol.

2. A flash-lamp comprising a'closed transparent bulb, an actinically reactive material in said bulb, and a gaseous filling in said bulb; said gaseous filling comprising oxygen for reacting with said actinically reactive material, and an auxiliary combustion-retarding gas; said auxiliary gas comprising no more than 10% by volume of said gaseous filling and comprising a halogen containing compound of one of the elements of the group boron, carbon, silicon, titanium, germanium and tin, and having a combustion heat lower than 200 kgs. cal./mol.

3. A flash-lamp comprising a closed transparent bulb, an actinically reactive material in said bulb, and a gaseous filling in said bulb; said gaseous filling comprising oxygen for reacting with said actinically reactive material, and an auxiliary combustion-retarding gas; said auxiliary gas comprising carbon tetrachloride.

4. A flash-lamp comprising a closed transparent bulb, an actinically reactive material in said bulb, and a gaseous filling in said bulb; said gaseous filling comprising oxygen for reacting with said actinically reactive material, and an auxiliary combustion-retarding gas; said auxiliary gas comprising trichloroethylene.

5. A flash-lamp comprising a closed transparent bulb, an actinically reactive material in said bulb, and a gaseous filling in said bulb; said gaseous filling comprising oxygen for reacting with said actinically reactive material, and an auxiliary combustion-retarding gas; said auxiliary gas comprising halogen containing compounds of the elements of the group boron, carbon, silicon, titanium, germanium and tin, and having a combustion heat lower than 200 kgs. caL/mol.

6. A flash-lamp comprising a closed transparent bulb, an actinically reactive material in said bulb, and a gaseous filling in said bulb; said gaseous filling comprising oxygen for reacting with said actinically reactive material, and an auxiliary combustion-retarding gas; said auxiliary gas comprising no more than 10% by volume of said gaseous filling and comprising halogen containing compounds of the elements of the group boron, carbon, silicon, titanium, germanium and tin, and having a combustion heat lower than 200 kgs. cal./mol.

JOHANNES ADRIAAN DE VRIEND. GERARD DANIEL RIECK.

REFERENCES CITED UNITED STATES PATENTS Name Date Van Liempt Mar. 30, 1943 Number 

